Electronic pen and electronic pen main body

ABSTRACT

An electronic pen includes a magnetic core that has a through-hole and around which a coil is wound in a direction along this through-hole, a core body that is inserted in the through-hole of this magnetic core and has electrical conductivity, a capacitor that forms a resonant circuit with the coil, a signal generation circuit that generates a signal that enables a position of the electronic pen to be detected, which is transmitted through the core body, an electricity storage device, and a charge circuit that charges the electricity storage device by an induced current generated in the coil according to an external magnetic field. While the resonant circuit operates, the signal generated by the signal generation circuit is concurrently transmitted through the core body.

BACKGROUND Technical Field

This disclosure relates to an electronic pen used with a positiondetecting device and an electronic pen main body used for thiselectronic pen.

Description of Related Art

In recent years, a coordinate input device has come to be used as aninput device of various pieces of electronic equipment and opportunitiesfor use of an electronic pen as an input tool of this coordinate inputdevice have been increasing. As the coordinate input device,conventionally the electromagnetic induction system is mainly used. Asone of this electromagnetic induction system, there is a system in whicha magnetic field from a sensor is received by a resonant circuitincluded in an electronic pen and return to the sensor is made (forexample, Patent Document 1 (refer to Japanese Patent Laid-open No.2009-86925)).

The coordinate input device of this electromagnetic induction system iscomposed of a position detecting device including a sensor obtained bydisposing a large number of loop coils in the X-axis direction and theY-axis direction of coordinate axes and an electronic pen as apen-shaped position indicator having a resonant circuit composed of acoil as an example of an inductance element wound around a magnetic coreand a capacitor.

The position detecting device supplies a transmission signal having apredetermined frequency to the loop coils of the sensor and transmitsthe signal to the electronic pen as electromagnetic energy. The resonantcircuit of the electronic pen is configured to have a resonancefrequency according to the frequency of the transmission signal andstores the electromagnetic energy based on the electromagnetic inductioneffect between the resonant circuit and the loop coils of the sensor.Then, the electronic pen returns the electromagnetic energy stored inthe resonant circuit to the loop coils of the sensor of the positiondetecting device.

The loop coils of the sensor detect the electromagnetic energy from thiselectronic pen. The position detecting device detects the coordinatevalues of the X-axis direction and the Y-axis direction regarding theposition on the sensor indicated by the electronic pen based on theposition of the loop coil that has supplied the transmission signal andthe position of the loop coil that has detected the electromagneticenergy from the resonant circuit of the electronic pen.

Furthermore, recently, a position detecting device of the capacitivecoupling system that is so used as to be overlapped on the front surfaceside of a liquid crystal display (LCD) as an example of a display hasalso been used for a portable device. Furthermore, a transmission-typeelectronic pen has come to be used and prized as an electronic pen usedwith this position detecting device of the capacitive coupling system.

This kind of electronic pen for the position detecting device of thecapacitive coupling system is a so-called active-system electronic penthat includes a battery and includes a signal transmitting circuitdriven by a voltage from this battery and supplies a transmission signalfrom this signal transmitting circuit to a position detecting sensor asa signal for position detection (for example, refer to Patent Document 2(Japanese Patent Laid-open No. 1995-295722) and so forth). As thebattery, besides a primary battery, a secondary battery of a chargesystem is also used. Meanwhile, the position detecting system uses asensor panel of position detecting means and carries out positiondetection as a position indicated by the position indicator from thesignal intensity of individual conductors that have received thetransmission signal from this active-system position indicator.

PRIOR ART DOCUMENTS Patent Documents

Patent Document 1: Japanese Patent Laid-open No. 2009-86925

Patent Document 2: Japanese Patent Laid-open No. 1995-295722

BRIEF SUMMARY Technical Problems

The above-described position detecting device of the electromagneticinduction system and the position detecting device of the capacitivecoupling system each have advantages and disadvantages. For electronicequipment, either system is employed according to the use purpose, useenvironment, and so forth thereof. For this reason, either one systemdoes not occupy the majority. Not only pieces of electronic equipmentthat employ the position detecting device of the electromagneticinduction system but also a large number of pieces of electronicequipment that employ the position detecting device of the capacitivecoupling system exist.

Conventionally, the user must prepare electronic pens compatible witheach of the electromagnetic induction system and the capacitive couplingsystem employed for the position detecting device of electronicequipment. Thus, while checking the system employed for the electronicequipment, the user needs to use the electronic pen according to thechecked system, which is troublesome. Furthermore, if the electronic penfor one system is lost, the electronic equipment to which this systemcorresponds becomes incapable of input by use of the position detectingdevice unless an electronic pen of the same system is newly purchased,which is inconvenient.

Furthermore, also for the manufacturing company, because the electronicpens for each of both systems of the electromagnetic induction systemand the capacitive coupling system must be each manufactured andprepared, there is a problem that a wide variety of parts are necessaryand the parts cost, the manufacturing cost, and the selling cost arehigh.

This disclosure provides an electronic pen that can solve one or more ofthe above problems.

Technical Solutions

In order to solve the above-described problems, claim 1 provides anelectronic pen including a magnetic core that has a through-hole andaround which a coil is wound in a direction along the through-hole, acore body that is inserted in the through-hole of the magnetic core andhas electrical conductivity, a capacitor that forms a resonant circuitwith the coil, a signal generation circuit that generates a signal thatenables a position of the electronic pen to be detected, the signalbeing transmitted through the core body, an electricity storage device,and a charge circuit which, in operation, charges the electricitystorage device by an induced current generated in the coil according toan external magnetic field, wherein, while the resonant circuitoperates, the signal generated by the signal generation circuit isconcurrently transmitted through the core body.

As described in claim 2, in a state in which the electronic penaccording to claim 1 with the above-described configuration is used witha sensor of an electromagnetic induction system, the electronic pen, inoperation, receives electromagnetic energy from the sensor and returnsthe received electromagnetic energy to the sensor by the resonantcircuit and charges the electricity storage device by the inducedcurrent generated in the coil.

Furthermore, as described in claim 3, in a state in which the electronicpen according to claim 1 with the above-described configuration is usedwith a sensor of a capacitive coupling system, the electronic pen, inoperation, transmits the signal generated by the signal generationcircuit to the sensor through the core body and charges the electricitystorage device by the induced current generated in the coil.

According to the electronic pen of this disclosure with theabove-described configuration, the electronic pen can be used as anelectronic pen for both systems of a position detecting device of theelectromagnetic induction system and a position detecting device of thecapacitive coupling system. In addition, according to the electronic penof this disclosure, there is an advantage that the electronic pen can beused as an electronic pen for position detecting devices of therespective systems without any switching operation between theelectromagnetic induction system and the capacitive coupling system.

Advantageous Effects

According to this disclosure, an electronic pen compatible with both ofa position detecting device of the electromagnetic induction system anda position detecting device of the capacitive coupling system can beprovided. In addition, according to the electronic pen of thisdisclosure, the electronic pen can be used as an electronic pen forposition detecting devices of the respective systems without anyswitching operation between the electromagnetic induction system and thecapacitive coupling system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are diagrams illustrating a configuration example of afirst embodiment of an electronic pen according to this disclosure.

FIGS. 2A and 2B are diagrams for explaining a configuration example ofan electronic pen main body used in the first embodiment of theelectronic pen according to this disclosure.

FIGS. 3A and 3B are diagrams for explaining a configuration example ofpart of the electronic pen main body used in the first embodiment of theelectronic pen according to this disclosure.

FIG. 4 is a diagram illustrating a configuration example of a signalprocessing circuit in the first embodiment of the electronic penaccording to this disclosure.

FIG. 5 is a diagram illustrating one example of a charger that chargesthe first embodiment of the electronic pen according to this disclosure.

FIG. 6 is a diagram illustrating an example of electronic equipment inwhich the first embodiment of the electronic pen according to thisdisclosure is used.

FIG. 7 is a diagram illustrating a configuration example of a positiondetecting device of the electromagnetic induction system used with thefirst embodiment of the electronic pen according to this disclosure.

FIG. 8 is a diagram illustrating a configuration example of a positiondetecting device of the capacitive coupling system used with the firstembodiment of the electronic pen according to this disclosure.

FIG. 9 is a diagram illustrating another configuration example of theposition detecting device of the capacitive coupling system used withthe first embodiment of the electronic pen according to this disclosure.

FIGS. 10A and 10B are diagrams for explaining aspects of a secondembodiment of the electronic pen according to this disclosure.

FIG. 11 is a diagram illustrating a configuration example of a signalprocessing circuit in the second embodiment of the electronic penaccording to this disclosure.

FIG. 12 is a diagram illustrating another configuration example of thesignal processing circuit in the second embodiment of the electronic penaccording to this disclosure.

FIG. 13 is a diagram for explaining a third embodiment of the electronicpen according to this disclosure.

FIG. 14 is a diagram illustrating a configuration example of a signalprocessing circuit in the third embodiment of the electronic penaccording to this disclosure.

FIG. 15 is a diagram illustrating a configuration example of a signalprocessing circuit in a fourth embodiment of the electronic penaccording to this disclosure.

MODES FOR CARRYING OUT THE DISCLOSURE

Embodiments of the electronic pen and the electronic pen main bodyaccording to this disclosure will be described below with reference tothe drawings.

First Embodiment

FIGS. 1A and 1B are diagrams illustrating a configuration example of afirst embodiment of an electronic pen according to this disclosure. Anelectronic pen 1 of this first embodiment has a knock-type configurationin which an electronic pen main body 3 is housed in a hollow part 2 a ofa tubular chassis 2 and the pen tip side of the electronic pen main body3 is protruded and retracted from the side of an opening 2 b at one endof the chassis 2 in the longitudinal direction by a knock cam mechanism4. In this embodiment, the electronic pen main body 3 is provided with acartridge-type configuration and is enabled to be attached and detachedto and from the chassis 2.

FIG. 1A illustrates a state in which the entire electronic pen main body3 is housed in the hollow part 2 a of the chassis 2. FIG. 1B illustratesa state in which the pen tip side of the electronic pen main body 3protrudes from the opening 2 b of the chassis 2 by the knock cammechanism 4. The example of FIGS. 1A and 1B is illustrated as the statein which the chassis 2 of the electronic pen 1 is composed of atransparent synthetic resin and the inside thereof is see-through.

The electronic pen 1 of this embodiment is configured to ensurecompatibility with a commercially-available knock-type ballpoint pen.

The chassis 2 and the knock cam mechanism 4 provided in this chassis 2have the same configuration as a well-known commercially-availableknock-type ballpoint pen and the dimensional relationship is alsoconfigured identically. In other words, it is also possible to use thechassis and the knock cam mechanism of the commercially-availableknock-type ballpoint pen as they are as the chassis 2 and the knock cammechanism 4.

As illustrated in FIG. 1, the knock cam mechanism 4 has a well-knownconfiguration in which a cam main body 41, a knock bar 42, and a rotaryelement 43 are combined. The cam main body 41 is formed on the innerwall surface of the tubular chassis 2. An end part 42 a of the knock bar42 is made to protrude from an opening 2 c on the side opposite to thepen tip side of the chassis 2 so that knock operation by a user can beaccepted. The rotary element 43 has a fitting part 43 a to which the endpart of the electronic pen main body 3 on the side opposite to the pentip side is fitted.

When the end part 42 a of the knock bar 42 is pressed down in the stateof FIG. 1(A), the electronic pen main body 3 is locked into the state ofFIG. 1B in the chassis 2 by the knock cam mechanism 4, which providesthe state in which the pen tip side of the electronic pen main body 3protrudes from the opening 2 b of the chassis 2. Then, when the end part42 a of the knock bar 42 is pressed down again from this state of FIG.1(B), the locked state is released by the knock cam mechanism 4 and theposition of the electronic pen main body 3 in the chassis 2 returns tothe state of FIG. 1A by a return spring 5. The return spring 5 isprovided between the knock cam mechanism 4 and a spring receiving member7. The spring receiving member 7 is attached to be fixed at apredetermined position in the axial center direction in the hollow partof the chassis 2, and a through-hole in which the electronic pen mainbody 3 is inserted is formed therein. The detailed configuration of theknock cam mechanism 4 of the electronic pen main body 3 and theoperation thereof are well known and therefore description thereof isomitted here.

Embodiment of Electronic Pen Main Body 3

FIGS. 2A and 2B are diagrams illustrating a configuration example of theelectronic pen main body 3 with comparison with a refill of acommercially-available knock-type ballpoint pen. Specifically, FIG. 2Aillustrates a refill 6 of the commercially-available knock-typeballpoint pen and FIG. 2B illustrates a configuration example of theelectronic pen main body 3 of this embodiment.

As illustrated in FIG. 2A , the refill 6 of the commercially-availableknock-type ballpoint pen has a well-known configuration in which a pentip part 61 in which a ball is disposed at the tip and an ink storage 62are joined at a joint part 63 and are integrated. The joint part 63 hasthe same diameter as the ink storage 62.

On the other hand, in the electronic pen main body 3 of this embodiment,a magnetic core, a ferrite core 32 in this example, around which a coil31 is wound is joined to a tubular body 33 as illustrated in FIG. 2B.Furthermore, a core body 34 is inserted through a through-hole(diagrammatic representation is omitted in FIGS. 2 A and 2B) of theferrite core 32 and, as described later, is fitted to a writing pressuredetection circuit (diagrammatic representation is omitted in FIGS. 2Aand 2B) provided in the tubular body 33 and is provided as part of theelectronic pen main body 3. As illustrated in FIGS. 2A and 2B, in thecore body 34, one end part 34 a (hereinafter, referred to as tip part 34a) protrudes from the ferrite core 32 as the pen tip.

FIG. 3A is an enlarged exploded view of the ferrite core 32 around whichthe coil 31 is wound, part of the tubular body 33, and the part of thecore body 34. The ferrite core 32 in this example is obtained by forminga through-hole 32 d in the axial center direction with a predetermineddiameter r (for example, r=1 mm), for insertion of the core body 34 in aferrite material having a circular column shape, for example. On the pentip side of this ferrite core 32, a taper part 32 e that graduallytapers is formed. Due to this taper part 32 e, magnetic flux that passesthrough this ferrite core 32 becomes high density at the taper part 32 eand magnetic coupling with the sensor of the position detecting devicecan be made stronger compared with the case in which the taper part 32 edoes not exist.

Furthermore, in this embodiment, as illustrated in FIG. 3A, the coil 31is not wound over the total length of the ferrite core 32 in the axialcenter direction but partly wound. Specifically, in this example, thecoil 31 is set to have a winding length that is approximately halflength of the total length of the ferrite core 32. In addition, asillustrated in FIG. 3A, a wound part 32 a of this coil in the ferritecore 32 is set at a position biased toward the side of the joint part tothe tubular body 33 in the ferrite core 32.

Furthermore, when the ferrite core 32 is seen in its axial centerdirection, the part from the end part on the pen tip side to one end ofthe coil-wound part 32 a is set as a first coil-non-wound part 32 baround which the coil is not wound. Moreover, a slight part from theother end of the coil-wound part 32 a to the side of the joint part tothe tubular body 33 in the ferrite core 32 is also set as a secondcoil-non-wound part 32 c around which the coil 31 is not wound. Thelength of the second coil-non-wound part 32 c in the axial centerdirection is set to a short length for the joining to the tubular body33. On the other hand, in this example, the length of the firstcoil-non-wound part 32 b in the axial center direction is set to acomparatively-long length obtained by subtracting the length of thesecond coil-non-wound part 32 c from approximately half length of thetotal length of the ferrite core 32.

Moreover, in this embodiment, a writing pressure detection circuit 35 isprovided near the joint part to the ferrite core 32 in the tubular body33. In this example, this writing pressure detection circuit 35 isprovided with a configuration of a variable-capacitance capacitor whosecapacitance changes according to the writing pressure, using writingpressure detecting means with a well-known configuration described inPatent Document: Japanese Patent Laid-open No. 2011-186803, for example.It is also possible for the writing pressure detection circuit 35 tohave a configuration using a semiconductor element that enables thecapacitance to vary according to the writing pressure like thatdisclosed in Japanese Patent Laid-open No. 2013-161307, for example.

A printed circuit board 36 is further housed in the tubular body 33.This printed circuit board 36 is provided with an oscillation circuit 37that forms an example of the signal generation circuit and a signalprocessing circuit (see FIG. 4) including a resonant circuit composed ofthe coil 31 and capacitors connected in parallel thereto (capacitor tobe described later and the variable-capacitance capacitor formed of thewriting pressure detection circuit 35) as described later.

Furthermore, as illustrated in FIG. 3B, all or part of the secondcoil-non-wound part 32 c of the ferrite core 32 is fitted to a concavepart 33 a made in the tubular body 33 and thereby the ferrite core 32 isjoined to the tubular body 33. Although diagrammatic representation isomitted, in this joining of the ferrite core 32 to the tubular body 33,ends 31 a and 31 b of the coil 31 are electrically connected to acapacitor 38 provided on the printed circuit board 36 in the tubularbody 33 so as to be connected in parallel to the capacitor 38.

As illustrated in FIG. 3A, the core body 34 is formed of a bar-shapedmember that has a diameter smaller than the diameter r of thethrough-hole of the ferrite core 32 and has electrical conductivity. Inthis example, the core body 34 is provided with a configuration of anelectrode core composed of a hard resin in which a conductor, e.g. anelectrically-conductive metal or electrically-conductive powders, ismixed. The core body 34 that forms this electrode core is connected tothe signal output terminal of the oscillation circuit 37 that forms thesignal transmitting circuit of the printed circuit board 36 by aconnecting line 39.

In the state in which the ferrite core 32 and the tubular body 33 arejoined, this core body 34 is inserted in the through-hole 32 d of theferrite core 32 from the side on which the taper part 32 e is formed asillustrated in FIG. 3B. Furthermore, in the core body 34, an end part 34b on the side opposite to the tip part 34 a thereof is fitted to afitting part 35 a of the writing pressure detection circuit 35 in thetubular body 33. In this case, although detailed diagrammaticrepresentation is omitted, e.g. an elastic material such as elasticrubber is disposed at the fitting part 35 a of the writing pressuredetection circuit 35 and the end part 34 b of the core body 34 is heldby this elastic material. This prevents the core body 34 from easilydropping off. However, when a user applies a force to withdraw the corebody 34, the fitting between the core body 34 and the fitting part 35 aof the writing pressure detection circuit 35 is easily released and thecore body 34 can be withdrawn. That is, the core body 34 is madereplaceable.

In the case of this example, as illustrated in FIG. 2A and FIG. 2B, theconfiguration is so made that the dimensions of the pen tip side of theelectronic pen main body 3 are almost equal to the dimensions of the pentip side of the refill 6 of the ballpoint pen. Specifically, theconfiguration is so made that the diameter of the ferrite core 32provided on the pen tip side of the electronic pen main body 3 is almostequal to diameter R1 of the pen tip part 61 of the refill 6 of theballpoint pen. Furthermore, the configuration is so made that the totallength of the length of the part protruding from the ferrite core 32 inthe tip part 34 a of the core body 34 and the length of the firstcoil-non-wound part 32 b of the ferrite core 32 is almost equal tolength L1 of the pen tip part 61 of the refill 6 of the ballpoint pen asillustrated in FIGS. 2A and 2B and FIG. 3B.

Furthermore, the diameter of the coil-wound part 32 a, around which thecoil 31 is wound, of the ferrite core 32 and the diameter of the tubularbody 33 in the electronic pen main body 3 are almost equal to diameterR2 of the ink storage 62 of the refill 6 of the ballpoint pen and arelarger than the diameter R1 of the above-described pen tip part 61 (R2>R1). The diameter of the opening 2 b of the chassis 2 is smaller thanthis diameter R2. Therefore, the coil-wound part 32 a cannot protrudefrom the opening 2 b to outside of the chassis 2.

Furthermore, as illustrated in FIGS. 2A and 2(B), the length (totallength) of the electronic pen main body in the state in which theferrite core 32 and the tubular body 33 are joined and the core body 34is fitted to the writing pressure detection circuit 35 in the tubularbody 33 through the through-hole of the ferrite core 32 is selected tobe equal to total length L2 of the refill 6 of the ballpoint pen.

The electronic pen main body 3 with the above configuration can behoused in the chassis 2 by causing the electronic pen main body 3 to beinserted in the through-hole of the spring receiving member 7 and thenfitting the tubular body 33 thereof to the fitting part 43 a of therotary element 43 of the knock cam mechanism 4.

Moreover, in the electronic pen 1 of this embodiment, a user pressesdown the end part 42 a of the knock bar 42 when using the electronic pen1 with a position detecting device. Thereupon, in the electronic pen 1,as illustrated in FIG. 1B and FIG. 3B, the state is obtained in whichthe tip part 34 a of the core body 34 and part of the firstcoil-non-wound part 32 b of the ferrite core 32 protrude from theopening 2 b of the chassis 2. In this state, the user of the electronicpen 1 carries out input operation of an indicated position over thesensor of the position detecting device.

When the use of the electronic pen 1 ends, the user presses down the endpart 42 a of the knock bar 42 again. Thereby, as illustrated in FIG. 1A,the entire electronic pen main body 3 can be set to the state of beinghoused in the hollow part 2 a of the chassis 2. At this time, the entireelectronic pen main body 3 is housed in the hollow part 2 a of thechassis 2 and the tip part 34 a of the core body 34 of the electronicpen main body 3 becomes the state of being protected by the chassis 2.

Next, a configuration example of the signal processing circuit of theelectronic pen 1 of this first embodiment will be described. FIG. 4 is adiagram illustrating a circuit configuration example of a signalprocessing circuit 300 of the electronic pen 1.

As illustrated in this FIG. 4, the capacitor 38 (see FIG. 3B) providedon the printed circuit board 36 and a variable-capacitance capacitor 35Cformed of the writing pressure detection circuit 35 are connected inparallel to the coil 31, so that a resonant circuit 300R is formed.Therefore, the resonance frequency of the resonant circuit 300R is setto a frequency according to the writing pressure detected in the writingpressure detection circuit 35.

Furthermore, in the electronic pen of this embodiment, this resonantcircuit 300R is connected to the oscillation circuit 37 as a circuitpart that decides the oscillation frequency of the oscillation circuit37 formed on this printed circuit board 36.

Moreover, in FIG. 4, 51 is an electric double-layer capacitor that formsan example of the electricity storage device, 52 is a rectificationdiode, and 53 is a voltage conversion circuit. In this example, one endof the coil 31 is connected to the anode of the rectification diode 52and the other end is grounded (GND). Furthermore, one end of theelectric double-layer capacitor 51 is connected to the cathode of therectification diode 52 and the other end is grounded. When analternating magnetic field exists outside the electronic pen 1, aninduced current is generated in the coil 31 and the induced current issupplied to the electric double-layer capacitor 51 through therectification diode 52 as a charging current, so that the electricdouble-layer capacitor 51 is charged and electricity is stored therein.

The core body 34 penetrates through the through-hole 32 d of the ferritecore 32, around which the coil 31 is wound, and is physically joined to(engaged with) the writing pressure detection circuit 35. In addition,for example, the core body 34 is electrically connected to theconnecting line 39 (see a dotted line in FIG. 3B) at the above-describedjoint part between the electrically-conductive core body 34 and thewriting pressure detection circuit 35. Furthermore, as described above,the connecting line 39 electrically connects the electrically-conductivecore body 34 and the oscillation circuit 37. Therefore, in theelectronic pen 1 of this embodiment, a configuration is made in which apressure (writing pressure) applied to the core body 34 is transmittedto the writing pressure detection circuit 35 by the above-describedphysical joint between the core body 34 and the writing pressuredetection circuit 35, which forms the variable-capacitance capacitor35C, and a transmission signal from the oscillation circuit 37 istransmitted from the core body 34 via the connecting line 39.

As described above, the resonant circuit 300R has a resonance frequencyaccording to the capacitance of the variable-capacitance capacitor ofthe writing pressure detection circuit 35, which changes according tothe writing pressure applied to the core body 34. Furthermore, theoscillation circuit 37 generates a signal whose frequency changesaccording to the resonance frequency of the resonant circuit 300R andsupplies the generated signal to the core body 34. The signal from theoscillation circuit 37 is radiated from the core body 34 as an electricfield based on the signal.

In this case, in the electronic pen 1, the coil 31 is at a fixedpotential (in this example, ground potential (GND)) and therefore thiscoil 31 acts as a shield electrode provided around the core body 34. Thefixed potential of the coil 31 is not limited to the ground potential.It may be a positive-side potential of the power supply or may be anintermediate potential between the positive-side potential of the powersupply and the ground potential.

The voltage conversion circuit 53 converts the voltage stored in theelectric double-layer capacitor 51 to a certain voltage and supplies thevoltage as the power supply of the oscillation circuit 37. This voltageconversion circuit 53 may be one of a buck type with which the voltageafter the conversion is lower than the voltage across the electricdouble-layer capacitor 51 or may be one of a boost type with which thevoltage after the conversion is higher than the voltage across theelectric double-layer capacitor 51. Furthermore, the voltage conversioncircuit 53 may be one of a buck-boost type that operates as a buckcircuit when the voltage across the electric double-layer capacitor 51is higher than the above-described certain voltage and operates as aboost circuit when the voltage across the electric double-layercapacitor 51 is lower than the above-described certain voltage.

FIG. 5 illustrates one example of a charger for the electronic pen 1 ofthis embodiment. A charger 310 of this example has an insertion port 312for the electronic pen 1 at part of a chassis 311. In addition, thecharger 310 includes a concave part that communicates with thisinsertion port 312 and has a support part 313 that supports theelectronic pen 1 inserted in this concave part. A coil 314 for powersupply is wound around the support part 313. The coil 314 for powersupply is connected to a charge control circuit 315. A plug 316 thatconnects to an outlet of a commercial alternating current (AC) powersupply is led out from the charge control circuit 315. In this example,the charge control circuit 315 drives the coil 314 for power supply togenerate an alternating magnetic field with a frequency almost equal tothe resonance frequency of the resonant circuit 300R.

When the electronic pen 1 of this embodiment is inserted in the concavepart of the support part 313 from the insertion port 312 of this charger310, an induced electromotive force is generated in the coil 31 of theelectronic pen 1 by the alternating magnetic field generated by thecharger 310 and charges the electric double-layer capacitor 51 throughthe rectification diode 52.

Circuit Configuration for Position Detection and Writing PressureDetection in Position Detecting Device Used with Electronic Pen 1

FIG. 6 illustrates one example of a tablet-type information terminal 200as an example of electronic equipment with which the electronic pen 1 ofthe embodiment of this disclosure is used as a position indicator. Inthis example, the tablet-type information terminal 200 includes adisplay screen 200D of a display device such as an LCD, for example.Furthermore, this kind of tablet-type information terminal 200 includesa position detecting device to which input can be carried out by usingthe position indicator. Moreover, as the position detecting device,terminals including a position detecting device 400EMR of theelectromagnetic induction system and terminals including a positiondetecting device 400AES of the capacitive coupling system exist. Theposition detecting device 400EMR of the electromagnetic induction systemis provided on the back side of the display device such as an LCD andthe position detecting device 400AES of the capacitive coupling systemis provided on the front side of the display device such as an LCD(upper side of the display screen).

As described at the beginning, conventionally, if the tablet-typeinformation terminal includes the position detecting device 400EMR ofthe electromagnetic induction system, a dedicated electronic pencorresponding to this position detecting device 400EMR of theelectromagnetic induction system needs to be used. Furthermore, if thetablet-type information terminal includes the position detecting device400AES of the capacitive coupling system, a dedicated electronic pencorresponding to this position detecting device 400AES of the capacitivecoupling system needs to be used. In contrast thereto, the electronicpen 1 of the embodiment with the above-described configuration can beused for either of the position detecting devices of both systems of theelectromagnetic induction system and the capacitive coupling system withno switching operation or the like.

Case in Which Position Detecting Device 400EMR of ElectromagneticInduction System Is Used

FIG. 7 is a diagram illustrating a circuit configuration example of theposition detecting device 400EMR of the electromagnetic induction systemthat carries out detection of the indicated position by the electronicpen 1 of the above-described embodiment and detection of the writingpressure applied to the electronic pen 1. As illustrated in FIG. 7, theposition detecting device 400EMR of this example is composed of aposition detecting sensor 410 and a pen detecting circuit 420 connectedto this position detecting sensor 410.

In the electronic pen 1, only the resonant circuit 300R in the signalprocessing circuit 300 of FIG. 4 is electromagnetically coupled to theposition detecting sensor 410 of the position detecting device 400EMR ofthe electromagnetic induction system as illustrated in this FIG. 7.Thereby, the electronic pen 1 carries out position indication andtransmission of the writing pressure.

In this case, in this embodiment, the electric double-layer capacitor 51is charged by the induced current that flows through the coil 31.Furthermore, the oscillation circuit 37 is also in an operating statedue to the voltage from the voltage conversion circuit 53 and thereforea signal is sent out to the position detecting device 400EMR through thecore body 34. However, in the position detecting device 400EMR, thesignal of the electric field coupling can be almost ignored comparedwith the signal transmitted and received by electromagnetic coupling andthus does not have an adverse effect in position indication anddetection of the writing pressure in the position detecting device400EMR.

In the position detecting device 400EMR, the position detecting sensor410 is formed by stacking an X-axis-direction loop coil group 411 and aY-axis-direction loop coil group 412. The respective loop coil groups411 and 412 are formed of e.g. n and m rectangular loop coils,respectively. The respective loop coils configuring the respective loopcoil groups 411 and 412 are disposed to line up at equal intervals andsequentially overlap with each other.

Furthermore, in the position detecting device 400EMR, a selectioncircuit 413 to which the X-axis-direction loop coil group 411 and theY-axis-direction loop coil group 412 are connected is provided. Thisselection circuit 413 sequentially selects one loop coil in the two loopcoil groups 411 and 412.

Moreover, the pen detecting circuit 420 of the position detecting device400EMR is provided with an oscillator 421, a current driver 422, aswitching connection circuit 423, a receiving amplifier 424, a detector425, a low-pass filter 426, a sample/hold circuit 427, an analog todigital (A/D) conversion circuit 428, a synchronous detector 429, alow-pass filter 430, a sample/hold circuit 431, an A/D conversioncircuit 432, and a processing control 433. The processing control 433 isformed of a microcomputer.

The oscillator 421 generates an AC signal with a frequency f0.Furthermore, the oscillator 421 supplies the generated AC signal to thecurrent driver 422 and the synchronous detector 429. The current driver422 converts the AC signal supplied from the oscillator 421 to a currentand sends out it to the switching connection circuit 423. The switchingconnection circuit 423 switches the connection target (transmission-sideterminal T or reception-side terminal R) to which the loop coil selectedby the selection circuit 413 is connected under control from theprocessing control 433. Of these connection targets, thetransmission-side terminal T is connected to the current driver 422 andthe reception-side terminal R is connected to the receiving amplifier424.

An induced voltage generated in the loop coil selected by the selectioncircuit 413 is sent to the receiving amplifier 424 via the selectioncircuit 413 and the switching connection circuit 423. The receivingamplifier 424 amplifies the induced voltage supplied from the loop coiland sends out the amplified voltage to the detector 425 and thesynchronous detector 429.

The detector 425 detects the induced voltage generated in the loop coil,i.e. the received signal, and sends out it to the low-pass filter 426.The low-pass filter 426 has a cutoff frequency sufficiently lower thanthe above-described frequency f0. The low-pass filter 426 converts theoutput signal of the detector 425 to a direct current (DC) signal andsends out it to the sample/hold circuit 427. The sample/hold circuit 427holds a voltage value at predetermined timing of the output signal ofthe low-pass filter 426, specifically at predetermined timing in thereception period, and sends out it to the A/D conversion circuit 428.The A/D conversion circuit 428 converts the analog output of thesample/hold circuit 427 to a digital signal and outputs it to theprocessing control 433.

Meanwhile, the synchronous detector 429 carries out synchronousdetection of the output signal of the receiving amplifier 424 with theAC signal from the oscillator 421 and sends out a signal at the levelcorresponding to the phase difference between them to the low-passfilter 430. This low-pass filter 430 has a cutoff frequency sufficientlylower than the frequency f0. The low-pass filter 430 converts the outputsignal of the synchronous detector 429 to a DC signal and sends out itto the sample/hold circuit 431. This sample/hold circuit 431 holds avoltage value at predetermined timing of the output signal of thelow-pass filter 430 and sends out it to the A/D conversion circuit 432.The A/D conversion circuit 432 converts the analog output of thesample/hold circuit 431 to a digital signal and outputs it to theprocessing control 433.

The processing control 433 controls the respective circuits of theposition detecting device 400EMR. Specifically, the processing control433 controls selection of the loop coil in the selection circuit 413,switching of the switching connection circuit 423, and the timing of thesample/hold circuits 427 and 431. Based on the input signals from theA/D conversion circuits 428 and 432, the processing control 433 makesradio waves be transmitted from the X-axis-direction loop coil group 411and the Y-axis-direction loop coil group 412 with a certain transmissioncontinuation time (continuous transmission section).

An induced voltage is generated in the respective loop coils of theX-axis-direction loop coil group 411 and the Y-axis-direction loop coilgroup 412 by radio waves transmitted (returned) from the electronic pen1. The processing control 433 calculates the coordinate values of theindicated position by the electronic pen 1 regarding the X-axisdirection and the Y-axis direction based on the level of the voltagevalue of this induced voltage generated in the respective loop coils.Furthermore, the processing control 433 detects the writing pressurebased on the level of the signal according to the phase differencebetween the transmitted radio waves and the received radio waves.

In this manner, the position detecting device 400EMR detects theposition of the electronic pen 1 that has come close to the positiondetecting device 400EMR by the processing control 433. In addition, theposition detecting device 400EMR obtains information on the writingpressure value of the electronic pen 1 by detecting the phase of thereceived signal.

Case in Which Position Detecting Device 400AES of Capacitive CouplingSystem Is Used

FIG. 8 is a diagram illustrating a circuit configuration example of theposition detecting device 400AES of the capacitive coupling system thatcarries out detection of the indicated position by the electronic pen 1of the above-described embodiment and detection of the writing pressureapplied to the electronic pen 1.

As illustrated in FIG. 8, the position detecting device 400AES of thisexample is composed of a position detecting sensor 440 and a pendetecting circuit 450 connected to this position detecting sensor 440.In this example, the position detecting sensor 440 is a component formedby stacking a first conductor group 441, an insulating layer(diagrammatic representation is omitted), and a second conductor group442 sequentially from the lower layer side although a sectional view isomitted. For example, the first conductor group 441 is a group obtainedby disposing plural first conductors 441Y₁, 441Y₂, . . . , and 441Y_(m),(m is an integer equal to or larger than 1) that extend along thehorizontal direction (X-axis direction) in the Y-axis direction inparallel, with the plural first conductors 441Y₁, 441Y₂, . . . , and441Y_(m) separated from each other by predetermined intervals.

Furthermore, the second conductor group 442 is a group obtained bydisposing plural second conductors 442X₁, 442X₂, . . . , and 442X_(n) (nis an integer equal to or larger than 1) that extend along a directionintersecting the extension direction of the first conductors 441Y₁,441Y₂, . . . , and 441Y_(m), the vertical direction (Y-axis direction)orthogonal to the extension direction in this example, in the X-axisdirection in parallel, with the plural second conductors 442X₁, 442X₂, .. . , and 442X_(n) separated from each other by predetermined intervals.

As above, the position detecting sensor 440 of the position detectingdevice 400AES has a configuration to detect a position indicated by theelectronic pen 1 by using the sensor pattern formed by making the firstconductor group 441 intersect the second conductor group 442.

In this case, in the electronic pen 1, a transmission signal from theoscillation circuit 37 in FIG. 4 is transmitted to the positiondetecting sensor 440 through the core body 34 having electricalconductivity. At this time, the resonant circuit 300R is also capable ofoperation. However, the position detecting sensor 440 of the positiondetecting device 400AES is not electromagnetically coupled to theresonant circuit 300R and thus detection of the indicated position anddetection processing of the writing pressure by the electronic pen 1 arenot affected.

In the following description, regarding the first conductors 441Y₁,441Y₂, . . . , and 441Y_(m), the conductor will be referred to as thefirst conductor 441Y when there is no need to discriminate therespective conductors. Similarly, regarding the second conductors 442X₁,442X₂, . . . , and 442X_(n), the conductor will be referred to as thesecond conductor 442X when there is no need to discriminate therespective conductors.

The pen detecting circuit 450 is composed of a selection circuit 451used as an input/output interface with the position detecting sensor440, an amplifying circuit 452, a band-pass filter 453, a detectioncircuit 454, a sample/hold circuit 455, an AD conversion circuit 456,and a control circuit 457.

The selection circuit 451 selects one conductor 441Y or 442X from thefirst conductor group 441 and the second conductor group 442 based on acontrol signal from the control circuit 457. The conductor selected bythe selection circuit 451 is connected to the amplifying circuit 452 anda signal from the core body 34 of the electronic pen 1 is detected bythe selected conductor and is amplified by the amplifying circuit 452.The output of this amplifying circuit 452 is supplied to the band-passfilter 453 and only a component of the frequency of the signaltransmitted from the core body 34 of the electronic pen 1 is extracted.

An output signal of the band-pass filter 453 is subjected to detectionby the detection circuit 454. An output signal of this detection circuit454 is supplied to the sample/hold circuit 455 and is sampled and heldat predetermined timing based on a sampling signal from the controlcircuit 457. Thereafter, the signal is converted to a digital value bythe AD conversion circuit 456. The digital data from the AD conversioncircuit 456 is read by the control circuit 457 and is processed.

The control circuit 457 operates to send out a control signal to each ofthe sample/hold circuit 455, the AD conversion circuit 456, and theselection circuit 451 based on a program stored in a read-only memory(ROM) inside the control circuit 457. Furthermore, the control circuit457 calculates position coordinates on the position detecting sensor 440indicated by the core body 34 of the electronic pen 1 from the digitaldata from the AD conversion circuit 456. In addition, the controlcircuit 457 detects the writing pressure detected in the writingpressure detection circuit 35.

Specifically, first, the control circuit 457 supplies a selection signalto sequentially select the second conductors 442X₁ to 442X_(n) to theselection circuit 451, for example. Furthermore, when each of the secondconductors 442X₁ to 442X_(n) is selected, the control circuit 457 readsdata output from the AD conversion circuit 456 as a signal level. Then,if the signal level of none of the second conductors 442X₁ to 442X_(n)reaches a predetermined value, the control circuit 457 determines thatthe electronic pen 1 does not exist over the position detecting sensor440, and repeats the control to sequentially select the secondconductors 442X₁ to 442X_(n).

If a signal at a level equal to or higher than the predetermined valueis detected from any of the second conductors 442X₁ to 442X_(n), thecontrol circuit 450 stores the number of the second conductor 442X fromwhich the highest signal level is detected and the numbers of pluralsecond conductors 442X around it. Then, the control circuit 457 controlsthe selection circuit 451 to sequentially select the first conductors441Y₁ to 441Y_(m), and reads the signal level from the AD conversioncircuit 456. At this time, the control circuit 457 stores the number ofthe first conductor 441Y from which the highest signal level is detectedand the numbers of plural first conductors 441Y around it.

Then, the control circuit 457 detects a position on the positiondetecting sensor 440 indicated by the electronic pen 1 from the numberof the second conductor 442X and the number of the first conductor 441Yfrom which the highest signal level is detected and the numbers of theplural second conductors 442X and the plural first conductors 441Yaround them, stored in the above-described manner.

Furthermore, the control circuit 457 detects the frequency of the signalfrom the AD conversion circuit 456 and detects the writing pressurevalue detected in the writing pressure detection circuit 35 from thedetected frequency. Specifically, as described above, the oscillationfrequency of the oscillation circuit 37 of the electronic pen 1 is thefrequency corresponding to the capacitance of the variable-capacitancecapacitor formed of the writing pressure detection circuit 35. Forexample, the control circuit 457 has information on a correspondencetable between the oscillation frequency of the oscillation circuit 37 ofthe electronic pen 1 and the writing pressure value and detects thewriting pressure value from this information on the correspondencetable.

In the example of the above description, the electronic pen 1 convertsthe writing pressure detected in the writing pressure detection circuit35 to the frequency and supplies a signal with the frequency to the corebody 34. However, the signal attribute to which the writing pressure ismade to correspond is not limited to the frequency and the writingpressure may be made to correspond to the phase of the signal, thenumber of times of intermittence of the signal, or the like.

Another Example of Position Detecting Device of Capacitive CouplingSystem

With the position detecting device 400AES of the capacitive couplingsystem illustrated in FIG. 8, the resonant circuit 300R is in theoperable state. However, an induced current is not generated in the coil31 thereof and thus the electric double-layer capacitor 51 is notcharged. Therefore, if the electronic pen 1 is used with the positiondetecting device 400AES of the capacitive coupling system over a longtime, the voltage stored in the electric double-layer capacitor 51 islowered. Thus, the use needs to be suspended and a charge needs to becarried out by using a charger, which is inconvenient.

Another example of this position detecting device of the capacitivecoupling system is an example of the case in which this point can beimproved. Specifically, FIG. 9 is a diagram illustrating a configurationexample of a position detecting device 401AES of the capacitive couplingsystem in this example. In this FIG. 9, the same parts as theabove-described position detecting device 400AES of the capacitivecoupling system are given the same reference symbols and descriptionthereof is omitted.

In the position detecting device 401AES of the capacitive couplingsystem in this example of FIG. 9, an excitation coil 443 is disposed tosurround the position detecting sensor 440. In FIG. 9, the excitationcoil 443 has two turns. However, in practice, the excitation coil 443 isset to have a larger number of turns, e.g. eight to ten turns. Asillustrated in FIG. 9, the excitation coil 443 is connected to a drivecircuit 458 and the drive circuit 458 is connected to an oscillationcircuit 459 that oscillates at the resonance frequency (centerfrequency) of the resonant circuit 300R, for example.

The drive circuit 458 is controlled by the processing control 457. Inthis example, when detecting reception of a signal from the electronicpen 1 based on the signal from the AD conversion circuit 456, theprocessing control 457 controls the drive circuit 458 and starts supplyof an oscillation signal from the oscillation circuit 459 to theexcitation coil 443 to supply electromagnetic energy from the excitationcoil 443 to the electronic pen 1.

An induced current is generated in the coil 31 of the resonant circuit300R of the electronic pen 1 due to an alternating magnetic field fromthis excitation coil 443. This induced current is supplied to theelectric double-layer capacitor 51 through the rectification diode 52 asa charge current, so that the electric double-layer capacitor 51 ischarged.

Therefore, if the position detecting device used with the electronic pen1 is the position detecting device 401AES of the capacitive couplingsystem in FIG. 9, there is an effect that the electronic pen 1 cansupply a signal from the oscillation circuit 37 to the positiondetecting sensor 440 of the position detecting device 401AES of thecapacitive coupling system through the core body 34 while charging theelectric double-layer capacitor 51 as an example of the electricitystorage device.

Effects of Above-described First Embodiment

As described above, according to the electronic pen 1 of theabove-described first embodiment, when this electronic pen 1 is broughtabove the position detecting sensor 410 of the position detecting device400EMR of the electromagnetic induction system, this electronic pen 1works as an electronic pen for a position detecting device of theelectromagnetic induction system by the resonant circuit 300R.Furthermore, when the electronic pen 1 is brought above the positiondetecting sensor 440 of the position detecting device 400AES of thecapacitive coupling system, this electronic pen 1 becomes the state inwhich a signal from the oscillation circuit 37 is sent out through thecore body 34, and works as an electronic pen for a position detectingdevice of the capacitive coupling system. Moreover, in the electronicpen 1 of the above-described first embodiment, the user does not need tocarry out any switching operation for both systems. Thus, the user canuse the electronic pen 1 without being aware of which of theelectromagnetic induction system and the capacitive coupling system theposition detecting device is based on, which is very convenient.

Furthermore, according to the electronic pen 1 of the above-describedfirst embodiment, the electronic pen 1 can be used with the positiondetecting device while charging the electric double-layer capacitor thatforms the electricity storage device.

Moreover, according to the electronic pen 1 of the above-described firstembodiment, information on the writing pressure detected in one writingpressure detection circuit 35 can be used as information for a positiondetecting device of the electromagnetic induction system and can also beused as information for a position detecting device of the capacitivecoupling system. Specifically, in the above-described first embodiment,the writing pressure detection circuit 35 is configured as a capacitorthat forms part of the resonant circuit 300R. In addition, this resonantcircuit 300R is used also as the circuit for deciding the oscillationfrequency of the oscillation circuit 37. Thus, to the position detectingdevice of the electromagnetic induction system, the information on thewriting pressure can be transmitted as change information of theresonance frequency of the resonant circuit. Furthermore, to theposition detecting device of the capacitive coupling system, theinformation on the writing pressure can be transmitted as changeinformation of the frequency of the signal sent out through the corebody 34.

Furthermore, according to the electronic pen 1 of the above-describedfirst embodiment, when the electronic pen 1 is used as an electronic penfor a position detecting device of the capacitive coupling system, thecoil 31 is set to a fixed potential and thus acts as a shield electrodefor the electrically-conductive core body 34 that sends out a signal.Therefore, even when the chassis 2 of the electronic pen 1 is held witha hand, the signal output by the core body 34 is not affected.

Moreover, according to the electronic pen 1 of the above-described firstembodiment, because of the configuration in which the coil 31 for acontactless charge is provided around the core body 34, a contactlesscharge by the charger 310 having a penholder shape is possible and anelectronic pen with favorable operability can be implemented.

In addition, according to the above-described first embodiment,reduction in the thickness of the electronic pen main body 3 can beimplemented. Thus, it becomes possible to enable the electronic pen mainbody 3 to have a configuration that enables ensuring of compatibilitywith a refill of a commercially-available ballpoint pen.

If the electronic pen main body 3 is provided with the configurationthat enables ensuring of compatibility with a refill of acommercially-available ballpoint pen, there is a merit that the chassisof the commercially-available ballpoint pen can be diverted as thechassis 2 of the electronic pen 1. That is, the electronic pen 1 can beconfigured by housing the electronic pen main body 3 of this embodimentinstead of a refill of the ballpoint pen in the chassis of the ballpointpen.

Second Embodiment

A second embodiment is an improvement example of the electronic pen 1 ofthe first embodiment. In the above-described first embodiment, theconfiguration is made in which the electronic pen 1 is set to the statein which a signal is constantly supplied from the oscillation circuit 37through the core body 34. For this reason, there is a problem thatstored electrical power of the electric double-layer capacitor 51 isdischarged if the electronic pen 1 is not mounted to a charger and notcharged when being in an unused state. The second embodiment is anexample in which this problem is solved. In the following description,the same parts as the electronic pen 1 of the above-described firstembodiment are given the same reference symbols and detailed descriptionthereof is omitted.

An electronic pen of this second embodiment is provided with detectingmeans that detects the time when the electronic pen 1 is in the unusedstate in which, as illustrated in FIG. 1A, the tip part 34 a of the corebody 34 does not protrude from the opening 2 b of the chassis 2 and theentire electronic pen main body 3 is housed in the chassis 2 and a usedstate of the electronic pen 1 in which, as illustrated in FIG. 1B, thetip part 34 a of the core body 34 is in a state of being protruded fromthe opening 2 b of the chassis 2 due to a knock operation in the knockcam mechanism 4.

In an electronic pen main body 3A of the case of this second embodiment,a tubular body 33A is provided with a switch that is turned on and offaccording to movement in the axial center direction by the knock cammechanism 4.

FIGS. 10A and 10B are diagrams for explaining the switch provided in theelectronic pen main body 3A. Specifically, in this example, athrough-hole 33Aa is made in the circumferential surface of apredetermined part of the tubular body 33A of the electronic pen mainbody 3A as illustrated in FIGS. 10A and 10B. In addition, a switch 8 isprovided in the tubular body 33A in such a manner as to be partlyexposed from this through-hole 33Aa.

In this case, the predetermined part of the tubular body 33A in whichthe through-hole 33Aa is made is a part of the tubular body 33A housedin the through-hole 7 a of the spring receiving member 7, which isprovided to be fixed in the chassis 2, in the state in which the entireelectronic pen main body 3A is housed in the chassis 2 of the electronicpen.

The switch 8 is composed of a material having elasticity and havingelectrical conductivity, e.g. an electrically-conductive metal havingelasticity. As illustrated in FIGS. 10A and 10B, this switch 8 iscomposed of a fixed terminal piece 81 fixed to the inner wall surfacenear the through-hole 33Aa of the tubular body 33A and a movableterminal piece 82 that can be elastically in contact with this fixedterminal piece 81. The movable terminal piece 82 includes a bent part 82a configured to be capable of assuming the state of being elastically incontact with the fixed terminal piece 81 and the non-contact state, andis attached to the inside of the tubular body 33A in such a manner thatpart of this bent part 82 a can protrude from the through-hole 33Aa.

When the electronic pen main body 3A is in the protected state in whichthe tip part 34 a of the core body 34 does not protrude from the opening2 b of the chassis 2 and exists in the hollow part of the chassis 2, theswitch 8 is located just in the through-hole 7 a of the spring receivingmember 7 as illustrated in FIG. 10A. Thus, the bent part 82 a of themovable terminal piece 82 is elastically displaced to the inside of thetubular body 33A due to the inner wall of the through-hole 7 a, whichprovides the state in which the fixed terminal piece 81 and the movableterminal piece 82 are not in contact with but separated from each other.That is, the switch 8 is in an off-state.

When the electronic pen main body 3A is in the used state of theelectronic pen in which the tip part 34 a of the core body 34 protrudesfrom the opening 2 b of the chassis 2 due to the knock cam mechanism 4,the switch 8 becomes the state of being out of the through-hole 7 a ofthe spring receiving member 7 as illustrated in FIG. 10B. Thereupon,part of the bent part 82 a of the movable terminal piece 82 iselastically displaced to protrude from the through-hole 33Aa, whichprovides a state in which the movable terminal piece 82 and the fixedterminal piece 81 are in contact with each other. That is, the switch 8is in an on-state.

FIG. 11 is a diagram illustrating one example of a signal processingcircuit 300A of the electronic pen of this second embodiment.Specifically, in the signal processing circuit 300A of the electronicpen of this second embodiment, a control circuit 54 is provided and aswitch circuit 55 is provided between the oscillation circuit 37 and thecore body 34. The fixed terminal piece 81 and the movable terminal piece82 of the switch 8 are electrically connected to the control circuit 54.Furthermore, this control circuit 54 supplies a switching control signalto the switch circuit 55 and supplies a control signal of theoscillation operation of the oscillation circuit 37.

The control circuit 54 monitors the on/off-state of this switch 8 tothereby detect whether or not the present state is the used state of theelectronic pen in which the tip part 34 a of the core body 34 of theelectronic pen main body 3A protrudes from the opening 2 b.

Furthermore, when the switch 8 is in the off-state as illustrated inFIG. 10A, the control circuit 54 determines that the electronic pen isin the unused state in which the tip part 34 a of the electronic penmain body 3A does not protrude from the opening 2 b, and turns off theswitch circuit 55 and controls the oscillation circuit 37 to a sleepstate (oscillation-stopped state). Due to this, in the unused state ofthe electronic pen, transmission of the signal from the oscillationcircuit 37 from the core body 34 is stopped and the operating state ofthe oscillation circuit 37 becomes the state of low power consumption,so that the consumption of the stored electrical energy of the electricdouble-layer capacitor 51 forming the electricity storage device isinhibited. At this time, when the electronic pen is mounted to thecharger 310, a charge is efficiently carried out.

Moreover, when the switch 8 is turned on as illustrated in FIG. 10B, thecontrol circuit 54 determines that the electronic pen is in the usedstate in which the tip part 34 a of the electronic pen main body 3Aprotrudes from the opening 2 b, and turns on the switch circuit 55 andcontrols the oscillation circuit 37 to the operating state. Due to this,in the used state of the electronic pen, the signal from the oscillationcircuit 37 is sent out from the core body 34.

In the unused state in which the tip part 34 a of the electronic penmain body 3A does not protrude from the opening 2 b, the resonantcircuit 300R also does not need to be operated. So, as illustrated inFIG. 12, a switch circuit 56 may be provided between the coil 31 and theparallel circuit of the capacitor 38 and the variable-capacitancecapacitor 35C and may be on/off-controlled similarly to the switchcircuit 55 by a switching control signal from the control circuit 54.

According to the above-described second embodiment, an effect thatuseless consumption of the stored electricity power of the electricitystorage device can be eliminated when the electronic pen is not used isachieved.

Note that in the examples of FIG. 11 and FIG. 12, supply of a signalfrom the oscillation circuit 37 to the core body 34 is controlled byproviding the switch circuit 55 between the oscillation circuit 37 andthe core body 34. However, the configuration may be so made that thesignal transmission from the core body 34 is stopped by providing theswitch circuit 55 on the supply path of the supply voltage from thevoltage conversion circuit 53 to the oscillation circuit 37 and stoppingthe power supply to the oscillation circuit 37 to thereby stop theoscillation of the oscillation circuit 37.

Third Embodiment

The above embodiments are the cases of the electronic pen with theconfiguration in which the electronic pen main body is housed in thechassis. However, this disclosure is not limited to an electronic pen ofa type in which such an electronic pen main body is configured to bereplaceable as a cartridge format, and it goes without saying that allfunctional components of the electronic pen main body may be configuredto be lined up in the chassis of the electronic pen. The thirdembodiment is an example of the electronic pen configured that way.

Furthermore, in this third embodiment, the electronic pen is configuredto be capable of being switched to a dedicated electronic pen between anelectronic pen for a position detecting device of the electromagneticinduction system and an electronic pen for a position detecting deviceof the capacitive coupling system.

FIG. 13 is a diagram for explaining the outline of the whole of anelectronic pen 1B of this third embodiment. Furthermore, FIG. 14 is adiagram for explaining an example of a signal processing circuit of theelectronic pen of this third embodiment. In the electronic pen 1B of thethird embodiment illustrated in FIG. 13 and FIG. 14, the partcorresponding to the above-described first embodiment and secondembodiment is given what is obtained by adding a suffix B to the samereference number as a reference symbol and description thereof will bemade.

As illustrated in FIG. 13, in the electronic pen 1B of this thirdembodiment, in a tubular chassis 2B, a ferrite core 32B (diagrammaticrepresentation is omitted in FIG. 13) around which a coil 31B(diagrammatic representation is omitted in FIG. 13) is wound and awriting pressure detection circuit 35B (diagrammatic representation isomitted in FIG. 13) are provided and a printed circuit board 36B isprovided similarly to the first embodiment described by using FIG. 3Band FIG. 4. Furthermore, a core body 34B is provided to be fitted to thewriting pressure detection circuit 35B through a through-hole of theferrite core 32B in the state in which a tip part 34Ba thereof alwaysprotrudes from the opening of the chassis 2B to the external. Also inthis third embodiment, the core body 34B is provided with a replaceableconfiguration similarly to the above-described embodiments.

Moreover, on the printed circuit board 36B, push switches 101 and 102that are in an on-state when being pressed down and return to anoff-state when the pressing-down is stopped are provided. In addition, acontrol circuit 100 that generates a control signal according to theon/off-state of the push switches 101 and 102 is provided. In addition,in an opening made in a side circumferential surface of the chassis 2B,pressing operation parts 101 a and 102 a composed of an insulating resinhaving elasticity, e.g. an acrylonitrile-butadiene-styrene (ABS) resin,are provided. The push switches 101 and 102 are turned on and off bypressing operation of these pressing operation parts 101 a and 102 a.

Furthermore, when the pressing operation part 101 a is operated to bepressed down, the push switch 101 is turned on. In response to this, thecontrol circuit 100 carries out settings to make the electronic pen 1Bbe an electronic pen for a position detecting device of theelectromagnetic induction system. Moreover, when the pressing operationpart 102 a is operated to be pressed down, the push switch 102 is turnedon. In response to this, the control circuit 100 carries out settings tomake the electronic pen 1B be an electronic pen for a position detectingdevice of the capacitive coupling system.

These push switches 101 and 102 and the control circuit 100 are includedin a signal processing circuit (diagrammatic representation is omittedin FIG. 13) formed similarly to the above-described embodiments on theprinted circuit board 36B.

FIG. 14 illustrates a configuration example of a signal processingcircuit 300B of this third embodiment. As illustrated in this FIG. 14,in this third embodiment, a resonant circuit 300RB is formed with thecoil 31B, a capacitor 38B provided on the printed circuit board 36B, anda variable-capacitance capacitor 35CB formed of the writing pressuredetection circuit 35B similarly to the above-described embodiments.Furthermore, this resonant circuit 300RB is connected as a circuit thatdefines the oscillation frequency of an oscillation circuit 37B.

Furthermore, similarly to the above-described embodiments, an inducedcurrent induced in the coil 31B according to an external magnetic fieldis supplied to an electric double-layer capacitor 51B through arectification diode 52B and thereby the electric double-layer capacitor51B is charged.

Moreover, in this third embodiment, a switch circuit 55B is providedbetween the oscillation circuit 37B and the core body 34B and a switchcircuit 57B is provided between the coil 31B and the rectification diode52B. The control circuit 100 switches the switch circuits 55B and 57Baccording to on/off-operation of the push switches 101 and 102.

In the electronic pen 1B of this third embodiment, when a user pressesdown the pressing operation part 101 a, the push switch 101 is turned onand the control circuit 100 turns off the switch circuits 55B and 57B.Thereupon, in the signal processing circuit 300B of the electronic pen1B, only the resonant circuit 300RB becomes effective and the electronicpen 1B becomes an electronic pen for the position detecting device ofthe electromagnetic induction system.

Furthermore, when a user presses down the pressing operation part 102 a,the push switch 102 is turned on and the control circuit 100 turns onthe switch circuits 55B and 57B. Thereupon, in the signal processingcircuit 300B of the electronic pen 1B, the state in which a signal fromthe oscillation circuit 37B is sent out through the core body 34B isobtained, and the electronic pen 1B becomes an electronic pen for aposition detecting device of the capacitive coupling system. In thesignal processing circuit 300B of the electronic pen 1B with thisconfiguration for a position detecting device of the capacitive couplingsystem, the electric double-layer capacitor 51B is charged through therectification diode 52 by an induced current induced in the coil 31B ifthe electronic pen 1B is used with a position detecting device includingthe excitation coil 443 illustrated in FIG. 9.

In the above-described manner, with the electronic pen 1B of this thirdembodiment, the user carries out pressing-down operation of the pressingoperation part 101 a or the pressing operation part 102 a according tothe system of the position detecting device to be used by the user andthereby can use the electronic pen 1B with selective switching of theelectronic pen 1B between an electronic pen for a position detectingdevice of the electromagnetic induction system and an electronic pen fora position detecting device of the capacitive coupling system.

In the configuration of FIG. 14, the switch circuit 55B may be providedon the supply path of the supply voltage between a voltage conversioncircuit 53B and the oscillation circuit 37B similarly to the examples ofFIG. 11 and FIG. 12.

Furthermore, on the outer circumferential surface of the chassis 2B,means that notifies the user of which of an electronic pen for aposition detecting device of the electromagnetic induction system and anelectronic pen for a position detecting device of the capacitivecoupling system the electronic pen 1B is set to may be provided. Forexample, by providing a light-emitting diode that is lit according topressing operation of the pressing operation parts 101 a and 102 a, theuser may be informed of which of an electronic pen for a positiondetecting device of the electromagnetic induction system and anelectronic pen for a position detecting device of the capacitivecoupling system the electronic pen 1B is set to. In this case, each onelight-emitting diode may be provided corresponding to a respective oneof the pressing operation parts 101 a and 102 a. Alternatively, onelight-emitting diode for either a position detecting device of theelectromagnetic induction system or a position detecting device of thecapacitive coupling system may be provided, and the user may be informedof setting for a position detecting device of the other system when theone light-emitting diode is not lit.

Fourth Embodiment

This fourth embodiment is another example of the case in which allfunctional components of the electronic pen main body are configured tobe lined up in the chassis of the electronic pen similarly to the thirdembodiment. In the above-described third embodiment, the electronic penis enabled to be set to a dedicated electronic pen between an electronicpen for a position detecting device of the electromagnetic inductionsystem and an electronic pen for a position detecting device of thecapacitive coupling system. However, similarly to the first embodiment,it is also possible to constantly set the resonant circuit and theoscillation circuit to the operating state in the signal processingcircuit. Furthermore, the electricity storage device may be not a systemthat is charged by an induced current in the coil of the resonantcircuit but a system that is directly charged by a charger.

This fourth embodiment is an example of the case in which the abovepoint is considered. In FIG. 15, a configuration example of a signalprocessing circuit 300C in the case of an electronic pen 1C of thisfourth embodiment is illustrated. In this FIG. 15, the partcorresponding to the above-described third embodiment is given what isobtained by adding C instead of the suffix B to the same referencenumber as a reference symbol and detailed description thereof isomitted.

In the signal processing circuit 300C of the electronic pen 1C of thisfourth embodiment, the rectification diode 52B is not provided.Therefore, the signal processing circuit 300C does not have theconfiguration to charge an electric double-layer capacitor 51C by aninduced current induced in a coil 31C of a resonant circuit 300RC. Inthis fourth embodiment, charge electrodes 58 and 59 are provided to beled out from both terminals of the electric double-layer capacitor 51C.These charge electrodes 58 and 59 are connected to charge electrodes ofa charger, for which diagrammatic representation is omitted, and theelectric double-layer capacitor 51C is charged by this charger.

Other Embodiments or Modification Examples

In the above-described embodiments, the variable-capacitance capacitorthat can vary the capacitance according to the writing pressure is usedas the writing pressure detection circuit. However, it goes withoutsaying that the writing pressure detection circuit may be what can varythe inductance value or the resistance value as long as it is a changeelement that changes the resonance frequency of the resonant circuit.

Furthermore, in the above-described embodiments, the writing pressuredetection circuit is provided. However, a switch that is turned onaccording to the pressure applied to the core body may be providedinstead of the writing pressure detection circuit, and the configurationmay be so made that the resonant circuit operates when this switch isturned on or the configuration may be so made that the oscillationcircuit starts oscillation. Furthermore, a threshold may be setregarding the pressure detected in the writing pressure detectioncircuit, and the configuration may be so made that the resonant circuitoperates when the pressure detected in the writing pressure detectioncircuit surpasses the threshold or the configuration may be so made thatthe oscillation circuit starts oscillation.

Moreover, as in the above-described first and second embodiments, it isalso possible to provide the electronic pen according to this disclosurewith a configuration of a so-called multicolor ballpoint pen in whichtwo or more ballpoint pen cores are provided in a chassis and oneballpoint pen core is selectively set to the use state by a knockmechanism by making the electronic pen main body have the samedimensions as a refill of a commercially-available ballpoint pen.

In addition, in the above-described first and second embodiments, theelectronic pen main body is made to have the same dimensions as a refillof a commercially-available ballpoint pen to enable intendingcompatibility between the chassis of the electronic pens 1 and 1M andthe chassis of the commercially-available ballpoint pen. However, it isobvious that the electronic pen main body reduced in thickness can beconfigured without considering the compatibility with a refill of acommercially-available ballpoint pen.

Furthermore, in the above-described first embodiment, the configurationis so made that the electronic pen main body is protruded and retractedinto the chassis based on the knock system by using the knock cammechanism. However, the electronic pen is not limited to such aknock-type electronic pen and may be an electronic pen with a form inwhich an electronic pen main body is simply housed in a chassis.

Moreover, in the electronic pens of the above-described first to thirdembodiments, information on the writing pressure detected in the writingpressure detection circuit is transmitted to a position detecting deviceas change in the resonance frequency in the resonant circuit. However,the transmitted information is not limited to the information on thewriting pressure. For example, a tilt detected by a tilt detectingsensor that detects the tilt of the electronic pen with respect to thesensor surface (indication input surface) may be transmitted as thechange in the resonance frequency.

In addition, in the above-described embodiments, the signal generationcircuit is so configured as to employ the oscillation signal itself ofthe oscillation circuit as the signal sent out through the core body.However, the signal generation circuit may be a configured to generatenot the oscillation signal itself of the oscillation circuit but asignal obtained by adding some kind of processing to the oscillationsignal through modulation of this oscillation signal or the like.

In the above-described embodiments, information on the writing pressuredetected in the writing pressure detection circuit is transmitted to aposition detecting device as change in the resonance frequency or changein the frequency of the oscillation signal. However, the method for thetransmission from the electronic pen to the position detecting device isnot limited to such a transmission method. For example, both of anelectronic pen of this disclosure and a position detecting device may beprovided with a wireless communication circuit of the Bluetooth(registered trademark) standards, for example and the information on thewriting pressure may be transmitted through the wireless communicationcircuit. Furthermore, not only the information on the writing pressurebut identification information (ID) of the electronic pen main body orthe electronic pen may be transmitted from the electronic pen to theposition detecting device through the wireless communication circuit.

DESCRIPTION OF REFERENCE SYMBOLS

1 . . . Electronic pen, 2 . . . Chassis, 2 b . . . Opening, 3 . . .Electronic pen main body, 4 . . . Knock cam mechanism, 31 . . . Coil, 32. . . Ferrite core, 34 . . . Core body, 35 . . . Writing pressuredetection circuit, 35C . . . Variable-capacitance capacitor, 36 . . .Printed circuit board, 37 . . . Oscillation circuit, 38 . . . Capacitor,300R . . . Resonant circuit, 400EMR . . . Position detecting device ofelectromagnetic induction system, 400AES . . . Position detecting deviceof capacitive coupling system, 443 . . . Excitation coil

1. An electronic pen comprising: a magnetic core that has a through-holeand around which a coil is wound in a direction along the through-hole;a core body that is inserted in the through-hole of the magnetic coreand has electrical conductivity; a capacitor that forms a resonantcircuit with the coil; a signal generation circuit which, in operation,generates a signal that enables a position of the electronic pen to bedetected, the signal being transmitted through the core body; anelectricity storage device; and a charge circuit which, in operation,charges the electricity storage device by an induced current generatedin the coil according to an external magnetic field, wherein, while theresonant circuit operates, the signal generated by the signal generationcircuit is concurrently transmitted through the core body.
 2. Theelectronic pen according to claim 1, wherein, in a state in which theelectronic pen is used with a sensor of an electromagnetic inductionsystem, the electronic pen, in operation, receives electromagneticenergy from the sensor and returns the received electromagnetic energyto the sensor by the resonant circuit and charges the electricitystorage device by the induced current generated in the coil.
 3. Theelectronic pen according to claim 1, wherein, in a state in which theelectronic pen is used with a sensor of a capacitive coupling system,the electronic pen, in operation, transmits the signal generated by thesignal generation circuit to the sensor through the core body.
 4. Theelectronic pen according to claim 1, wherein, in a state in which theelectronic pen is used with a sensor of a capacitive coupling system,the electronic pen, in operation, charges the electricity storage deviceby the induced current generated in the coil if the external magneticfield is received by the electronic pen and transmits the signalgenerated by the signal generation circuit to the sensor through thecore body.
 5. The electronic pen according to claim 1, wherein theelectronic pen, in operation, charges the electricity storage device bythe induced current generated in the coil if the external magnetic fieldis received by the electronic pen.
 6. The electronic pen according toclaim 1, further comprising: a writing pressure detection circuit,wherein one end of the core body inserted in the through-hole of themagnetic core is protruded from the through-hole of the magnetic coreand is used as a pen tip, and an end of the core body opposite to theone end that is protruded from the through-hole of the magnetic core iscoupled to the writing pressure detection circuit.
 7. The electronic penaccording to claim 6, wherein the core body is coupled to the writingpressure detection circuit insertably and removably and is replaceable.8. The electronic pen according to claim 6, wherein the writing pressuredetection circuit, in operation, varies a resonance frequency of theresonant circuit according to an applied writing pressure, and isconnected to the resonant circuit.
 9. The electronic pen according toclaim 8, wherein the signal generation circuit includes an oscillationcircuit, and the resonant circuit, in operation, varies a frequency ofan oscillation signal generated by the oscillation circuit.
 10. Theelectronic pen according to claim 1, further comprising: a switch which,in operation, switches between a state in which the signal generated bythe signal generation circuit is transmitted through the core body and astate in which the signal generated by the signal generation circuit isblocked from being transmitted through the core body.
 11. The electronicpen according to claim 1, further comprising: a switch which, inoperation, is switched between a state in which the capacitor isconnected to the coil and a state in which the capacitor is disconnectedfrom the coil.
 12. The electronic pen according to claim 1, furthercomprising: a switch which, in operation, is switched between a state inwhich the electricity storage device is charged by the induced currentgenerated in the coil according to the external magnetic field and astate in which a charge to the electricity storage device is stopped.13. The electronic pen according to claim 1, further comprising: adetermination circuit which, in operation, determines whether theelectronic pen is in a used state or in an unused state based on anoperation state of an operation part that is operable by a user; and aswitch circuit that is switched between a state in which the signalgenerated by the signal generation circuit is transmitted through thecore body and a state in which transmission of the signal generated bythe signal generation circuit through the core body is blocked, whereinthe switch, in operation, is switched to the state in which thetransmission of the signal generated by the signal generation circuitthrough the core body is blocked when the determination circuitdetermines that the electronic pen is in the unused state.
 14. Theelectronic pen according to claim 1, further comprising: a determinationcircuit which, in operation, determines whether the electronic pen is ina used state or in an unused state based on an operation state of anoperation part that is operable by a user; and a first switch circuitwhich, in operation, is switched between a state in which the signalgenerated by the signal generation circuit is transmitted through thecore body and a state in which transmission of the signal generated bythe signal generation circuit through the core body is blocked, and asecond switch circuit which, in operation, is switched between a statein which the capacitor is connected to the coil and a state in which thecapacitor is disconnected from the coil, wherein the first switchcircuit, in operation, is switched to the state in which thetransmission of the signal generated by the signal generation circuitthrough the core body is blocked and the second switch circuit isswitched to the state in which the capacitor is disconnected from thecoil when the determining circuit determines that the electronic pen isin the unused state.
 15. An electronic pen comprising: a tubular chassisin which an opening is made on one end in an axial center directionserving as a pen tip side and another end is closed; and an electronicpen main body housed in the tubular chassis, wherein the electronic penmain body includes: a magnetic core that has a through-hole and aroundwhich a coil is wound in a direction along the through-hole, a core bodythat is inserted in the through-hole of the magnetic core and haselectrical conductivity, a capacitor that forms a resonant circuit withthe coil, a signal generation circuit which, in operation, generates asignal that enables a position of the electronic pen main body to bedetected, the signal being transmitted through the core body, anelectricity storage device, and a charge circuit which, in operation,charges the electricity storage device by an induced current generatedin the coil according to an external magnetic field, wherein, while theresonant circuit operates, the signal generated by the signal generationcircuit is concurrently transmitted through the core body.
 16. Theelectronic pen according to claim 15, further comprising: a knockmechanism of a knock-type ballpoint pen coupled to the electronic penmain body in the chassis.
 17. The electronic pen according to claim 16,further comprising: a detection circuit which, in operation, detectswhether the electronic pen is set to a used state in which part of thecore body protrudes externally from the chassis through the opening byoperation of the knock mechanism or is set to an unused state in whichall of the core body is located inside the chassis, and a first switchcircuit which, in operation, switches a path of the signal generated bythe signal generation circuit and the core body between a connectedstate and a blocked state, and a second switch circuit which, inoperation, is switched between a state in which the capacitor isconnected to the coil and a state in which the capacitor is disconnectedfrom the coil, wherein, in operation, the first switch circuit isswitched to the blocked state and the second switch circuit is switchedto the state in which the capacitor is disconnected from the coil whenthe detection circuit detects that the electronic pen is set to theunused state in which all of the core body is located inside thechassis.
 18. An electronic pen main body having at least a pen tiphoused in a tubular chassis of an electronic pen, the pen tip beingprotrudable from an opening on one side of the tubular chassis in anaxial center direction, the electronic pen main body comprising: amagnetic core that has a through-hole and around which a coil is woundin a direction along the through-hole; a core body that is inserted inthe through-hole of the magnetic core and has electrical conductivity; acapacitor that forms a resonant circuit with the coil; a signalgeneration circuit which, in operation, generates a signal that enablesa position of the electronic pen main body to be detected, the signalbeing transmitted through the core body; an electricity storage device;and a charge circuit which, in operation, charges the electricitystorage device by an induced current generated in the coil according toan external magnetic field, wherein, while the resonant circuitoperates, the signal generated by the signal generation circuit isconcurrently transmitted through the core body.